The goal of the Transgenic Mouse Core Facility is to provide investigators at the Joslin with a centralized resource for the production of transgenic animals by DNA microinjection and by embryonic stem (ES) cell injection. The microinjection of embryos and the microsurgical procedures to produce transgenic animals requires specialized equipment, animal housing, and highly skilled personnel. The Transgenic Mouse Core Facility provides these resources to investigators, and in addition to providing expert advice and training in the generation, care, and maintenance of transgenic and knockout mice.